<!DOCTYPE html>
<html>
<body>
  <script>
    function createIframe() {
      const iframe = document.createElement('iframe');
      iframe.src = `data:text/html,
<!DOCTYPE html>
<html>
<body>
<style>
p {
  font-size: 40px;
}
</style>
<p>
This is bigger text than main frame content!!!!
</p>
</body>
</html>`;
      document.body.appendChild(iframe);
    }
  </script>
  <button id='button' onclick="createIframe()">A</button>
</body>
</html>
